TinyLinux
TinyLinux is a project led by Matt Mackall to reduce the size of the Linux kernel, in both memory usage and binary filesize. It is also known as the -tiny tree.
TinyLinux consists of a set of patches against the Linux kernel which make certain features optional, or add system monitoring and measurement so that further optimization can take place. They are made to be mergeable with the mainline kernel, and many patches have been merged to date.
Features include: the ability to disable ELF core dumps, reduce the number of swap files, use of the SLOB memory allocator, ability to disable BUG(). For measuring and accounting features include: ability for kmalloc/kfree allocations to be monitored through /proc/kmalloc; and measurement of inline usage during kernel compiling.